A knowledge of the stimuli which regulate the expression of a given behavior is essential to a full understanding of that behavior. The objectives of the proposed research are to explore the range of pup stimuli (normal and altered) capable of inducing (in virgins), initiating and maintaining (following Cesarean delivery or restricted parturition experience) maternal responsiveness in rats. In virgins, the role of pup licking will be focussed on during Priming (15 min/day X 8 days of pups in the test female's cage) by manipulations of pups or test females which either increase of decrease the likelihood of pup licking (e.g. addition of urine vs. vaseline covering). The effects of continuous exteroceptive stimulation from pups will be assessed as well. The role of parturition experiences per se, and of prepartum and parturitional events (i.e., genital self-licking; oxytoxin secretion; vaginal stimulation) will be explored. Experiments on ovarian steroid primed rats and Cesarean-delivered rats will be carried out to see if peri-parturitional events are important in facilitating the very rapid and reliable appearance of maternal behavior characteristic of the parturient rat. Finally, the influence of parturition experience and subsequent maternal behavior experience on the transition from pup selectivity to pup generalization will be explored. The effects of premature and Cesarean childbirth and amount of maternal-baby contact in the immediate post-delivery period on parent-infant interactions and establishment of successful breastfeeding have received considerable attention in the obstetric, pediatric and infancy literatures. Thus, the proposed research may provide an animal model for the crucial role of physical interaction with young (especially during sensitive periods, such as postpartum) on the induction, initiation and maintenance of maternal responsiveness.